Recombinant Soluble CD32 Suppresses Disease Progression in Experimental Epidermolysis Bullosa Acquisita  Hiroaki Iwata, Elena Pipi, Nicole Möckel, Peter Sondermann, Artem Vorobyev, Nina van Beek, Detlef Zillikens, Ralf J. Ludwig  Journal of Investigative Dermatology  Volume 135, Issue 3, Pages 916-919 (March 2015) DOI: 10.1038/jid.2014.451 Copyright © 2015 The Society for Investigative Dermatology, Inc Terms and Conditions

Figure 1 sCD32 inhibits neutrophil activation ex vivo by immune complexes (IC). (a) IC were generated by incubation of human IgG on 96-well plates. After washing, human neutrophils were added in the presence or absence of sCD32. Neutrophil activation was assayed by measuring reactive oxygen species (ROS) production. sCD32 inhibited ROS production from IC-activated neutrophils in a dose-dependent manner. Data are based on five experiments, using different leukocyte donors, per group (*P<0.05, analysis of variance (ANOVA)), and expressed as mean±SEM. (b) Cryosections from normal human skin were incubated with sera from bullous pemphigoid (BP) patients. Subsequently, leukocytes from healthy blood donors were added. This induced dermal–epidermal separation in the absence of sCD32. In the presence of sCD32, autoantibody-induced, leukocyte-dependent dermal–epidermal separation was significantly impaired. Data are based on 21 experiments, that is, different BP sera and leukocyte donors, per group (*P<0.05 vs. positive control, ANOVA), and expressed as mean±SEM. (c) Similar results were obtained when incubating normal human skin with epidermolysis bullosa acquisita (EBA) patient IgG (n=1) and leukocytes from healthy blood donors (n=5). In all sections incubated with EBA patient IgG, dermal–epidermal separation was induced; in contrast to the experiments using BP sera, a wider variation was observed (ranging from 2% to 100%). Therefore, data were normalized to the dermal–epidermal separation of the positive control (set at 100%). Simialar to experiments using BP patient serum, sCD32 also impaired dermal–epidermal separation induced by EBA serum. Compared with positive EBA control serum, dermal–epidermal separation was reduced to 61±6% in sCD32-treated sections (concentration: 0.5 mg ml-1; P<0.001, t-test). A representative example of each treatment group from a total of five experiments is demonstrated. Asterisks indicate the position of dermal–epidermal junction without any separation, and arrows indicate areas of dermal–epidermal separation. Bar=200 μm. Journal of Investigative Dermatology 2015 135, 916-919DOI: (10.1038/jid.2014.451) Copyright © 2015 The Society for Investigative Dermatology, Inc Terms and Conditions

Figure 2 sCD32 suppresses progression of already established experimental epidermolysis bullosa acquisita (EBA). (a) Arrow at week 0 indicates starting point of treatment (left). Compared with phosphate-buffered saline (PBS)-injected mice, sCD32 treatment led to significantly fewer skin lesions. Data are based on total 13 mice per group (left, *P<0.05, t-test), and expressed as mean±SEM. Overall, clinical disease severity (area under the curve (AUC)) was lower in mice treated with sCD32 (right, P=0.031, t-test). (b) Representative clinical pictures 4 weeks after allocation to PBS (left) or sCD32 treatment (right). (c) The score of dermal infiltrates was significantly lower in mice treated with sCD32 (P<0.05, t-test). Representative hematoxylin and eosin (H&E)-stained sections of skin from mice treated with sCD32 (right) or PBS (left) are shown. Numbers in upper right corners indicate the mean±SEM of the semiquantitative scored infiltration, ranging from 0 (no infiltration) to 3 (severe dermal infiltration). Bar=200 μm. (d) Mice treated with sCD32 had ∼20% less autoantibodies compared with control (P=0.048; t-test). (e) The fluorescence intensity of IgG was not different. Representative pictures of IgG deposits. Bar=50 μm. Journal of Investigative Dermatology 2015 135, 916-919DOI: (10.1038/jid.2014.451) Copyright © 2015 The Society for Investigative Dermatology, Inc Terms and Conditions